Can hillstream loaches live with harlequin rasboras?

Verdict
Yes

Yes. Hillstream loaches and harlequin rasboras make a good pair. Both are fine at 72–75°F. Plan on at least 20 gal.

Hillstream loachHillstream loach68–75°F · pH 6.5–7.5 Harlequin rasboraHarlequin rasbora72–80°F · pH 6–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 72–75°Hillstream loach 68–75°Harlequin rasbora 72–80°
The green band is the temperature range both can live in.
456789Both: 6.5–7.5Hillstream loach 6.5–7.5Harlequin rasbora 6–7.5
The green band is the pH both tolerate.

Size to scale

Hillstream loach · 2.5 inHarlequin rasbora · 2 in0"1"2"3"4"5"6"
Adult length in an aquarium. A fish can swallow anything that fits in its mouth, roughly a third to half its own length for predators.

Care at a glance

Hillstream loachHarlequin rasbora
Temperature68–75 °F72–80 °F
pH6.5–7.56–7.5
Adult size2.5 in2.0 in
Minimum tank20 gal10 gal
TemperamentPeacefulPeaceful
Swims atBottomMiddle
GroupGroups of 3+Groups of 6+
DietHerbivoreOmnivore

Better tank mates for hillstream loaches

All hillstream loach tank mates

Better tank mates for harlequin rasboras

All harlequin rasbora tank mates

Questions

Can hillstream loaches live with harlequin rasboras?

Yes. Hillstream loaches and harlequin rasboras make a good pair. Both are fine at 72–75°F. Plan on at least 20 gal.

What temperature suits both hillstream loaches and harlequin rasboras?

72–75 °F. Hillstream loaches need 68–75 °F, harlequin rasboras need 72–80 °F.

What size tank do hillstream loaches and harlequin rasboras need together?

At least 20 gal, set by the hillstream loach. Add space for each extra fish.